Primer pocket swaging is necessary when reloading brass that have crimped primer pockets, most cases used in military or non civilian applications have this crimp. Typical cases that you will encounter primer pocket crimps are 45 ACP, 223(5.56mm), 30-06, 308(7.62x51), 9mm Luger and special law enforcement 40 S&W. The hardened steel swage punch is automatically extracted from the primer pocket by five 400 pound force disc springs. Swage holder, large or small, installs in seconds into your press ram with no adjustments required. Primer pocket swaging is so fast you'll want to swage all range brass.